    
    .lbt .imgBox{
        position: fixed;
        top: 0;
        z-index: -1;
        width: 100%;
        height: 100%;
    }

    .lbt .imgBox img{
        width: 100%;
        height: 100%;
    }

    .lbt .img1{
        display: block;
    }

    .lbt .img2{
        display: none;
    }

    .lbt .img3{
        display: none;
    }

    .lbt .img4{
        display: none;

    }